Stator blade assembly for turbo machines

ABSTRACT

The stator blades of a stage of an axial flow turbo machine are assembled in an arcuate series, as by insertion of the journals at the outer ends of the blades in the stator housing. A onepiece arcuate inner shroud ring is formed with aperture spaced circumferentially comparable to the spacing of the inner ends of the blades in the series. The diameter of the apertures exceeds the diameter of the blade journals. Force is applied to the ends of the ring to control or bow the same sufficiently to permit insertion of the contracted ring into the series of blades. Upon insertion of the ring, the contracting force is relieved, permitting the ring to expand to normal contour whereby the inner journals of the blades become positioned in the apertures of the ring. Thereafter annular bearings are inserted in the space between the journals and the bores of the apertures.

United States Patent Sheilds et al.

1 1 June 10, 1975 [541 Q BLADE ASSEMBLY FOR TURBO FOREIGN PATENTS ORAPPLICATIONS MA INES 15.893 7/1908 United Kingdom 415/217 [76]Inventors: J. Rodger Sheilds, 1601 Penn Ave.

Pittsburgh, Pa. 15206; Alexander A. Primary Examiner w Lanham Carroll,30m Assistant ExaminerDan C. Crane Greensburg, Pa. 15601 [22] Filed:Feb. 26, 1973 [57] ABSTRACT [211 App]. 335,973 The stator blades of astage of an axial flow turbo machine are assembled in an arcuate series,as by inser- Related Appllcanon Data tion of the journals at the outerends of the blades in [62} Division of Ser. No, 112,163. Feb. 3, 1971,the stator housing. A one-piece arcuate inner shroud abandoned ring isformed with aperture spaced circumferentially comparable to the spacingof the inner ends of the Cl 29/1563 29/446; 415/217; blades in theseries. The diameter of the apertures ex- 4l5/219 R ceeds the diameterof the blade journals. Force is apll'llt. to the ends f the ring toontrol or bow the Field Or Search 29/1558 446, same sufficiently topermit insertion of the contracted 415/217. 8, 219 ring into the seriesof blades. Upon insertion of the ring, the contracting force isrelieved, permitting the [56] RefETBIICeS Clled ring to expand to normalcontour whereby the inner UNITED STATES PATENTS journals of the bladesbecome positioned in the aper- 839243 12906 Wilkinson IIIIIIIIIIIIIIIIII219N563 R tures of the ring. Thereafter annular bearings are in- |5g 755[M915 w 4 Y v H 5 g R serted in the space between the journals and thebores 1,621,002 3/1927 Dimberg 29/1568 R of the apertures, 2,856,11810/1958 Smith r 1. 415/217 3 Cl 4 D 1212.317 2/1905 Fullagar 29/1561; R

I5 37 4o 37 1? F. lc I Yfil M l III JFHTFMHH 0 ms 3.887; 976 SHEET 1INVENTOR. J. RODGER SHIELDS BYALEXANDER CARROLL ATTORNEY SHEU YATENTEUJUH 10 I975 BY 5 ARROLL ATTORNEY m 0; WWW v 0: N 4 6 mm mm Q 7 Z 8 R f 8STATOR BLADE ASSEMBLY FOR TURBO MACHINES This is a division. ofapplication Ser. No. 112.163 filed Feb. 3. 1971. now abandoned.

BACKGROUND OF THE INVENTION In some types of multistage axial flow turbomachines. the stator blades are fixedly mounted in the stator housing bylocking the tangs. or journals. at the outer ends of the blades to thestator housing. In large high speed machines. the stator blades aresubjected to forces of substantial magnitude tending to create avibratory condition in the blades. To reduce such vibration. innershroud rings have been fixedly secured to the inner ends of the fixedblades; for example. as shown in US. Pat. No. 3.269.701. assigned to theassignee herein.

In turbo machines for certain applications. it is desirable to mount atleast one row of the stator blades for rotative adjustment about theirlengthwise axis. To eliminate excessive vibration in the adjustableblades. it is necessary to provide a relatively close running fitbetween the blade journals and stator housing and the inner shroud ring.In view of the mounting of the blades for rotation. problems areencountered in the manufacture and assembly of the inner shroud rings tothe blades to provide the proper support thereof. and to provide freeadjustment of the blades under operating conditions.

This invention has as an object a stator blade assembly structurewherein the inner shroud ring is of simple one-piece construction.economical to manufacture and which is quickly and conveniently mountedon the inner ends of an arcuate series of stator blades.

SUMMARY OF THE INVENTION The stator blades of a stage are arranged in anarcuate series. which arrangement can be had by inserting the journalsat the outer ends of the blades in apertures formed in the statorhousing. and a one-piece shroud ring of arcuate configuration is formedwith oversized apertures to receive projections at the inner ends of thecircular series of blades. The ring is applied to the blades of theseries by being contracted to reduce the chord dimension of the ringsufficient to clear the inner ends of the blades when the ring isinserted in the series. Upon release of the contraction force. the ringexpands to its normal contour. moving the apertures of the ring over thejournals at the inner ends of the blades. With the ring so positioned.in the arcuate series of stator blades. annular bearing members are inserted in the apertures and have a close running fit with the ends ofthe blades. The bearings are locked in the apertures.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustrationshowing a preferred embodiment of the invention wherein the blades of astage of the machine are arranged in an arcuate series in the statorhousing. and illustrating the inner shroud ring in contracted formpositioned for insertion in the series of blades. the housing and shroudring being illus' trated in sections.

FIG. 2 is a view similar to FIG. I showing the shroud ring insertedfarther in the series of blades.

FIG. 3 is an enlarged view taken on line III-III of FIG. 2.

FIG. 4 is an enlarged sectional view of the inner shroud ring and bladejournal structure shown in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the fragmentarysectional view of FIG. 3, the shaft structure ofthe turbo machine isdesignated 10, and has affixed to it a series of axially arranged discsII. Each disc 11 carries a circular series of rotor blades 12, therebeing a disc and series of blades 12 for each stage of the machine. Theblades 12 are encircled by a stator housing 13 which conventionallyconsists of two semi-circular sections having side bosses l boltedtogether. FIGS. 1 and 2.

A circular series of stator blades 17 is mounted intermediate eachseries of spaced rotating blades 12. The blades 17 are provided at theirouter ends with projections in the form of tangs 20. which extendoutwardly through apertures formed in the stator housing 13.

The inner ends of the stator blades I7 are provided with projections orjournals. which may be formed integral with the blades. or as shown inFIG. 4. may consist of annular collar members positioned on a tangportion 27, the outer end of which is headed over as shown at 28 tofixedly secure the collars 25 to the blades I7. Preferably the journals25 are formed with radial flanges 26 abutting against the inner end ofthe blade.

A one-piece shroud ring section 30. shown in the pre ferred embodimentas being of semi-circular form. is provided with a series of apertures33 spaced circumferentially along the ring comparable to the spacing ofthe inner ends of the blades I7. These apertures have a bore somewhatlarger than the diameter of the collars 25 as indicated by the annularspace 35. FIG. 4. encircling the periphery of the collar 25. Theseapertures are dimensioned so that upon applying a contracting forceinwardly on the ends of the ring 30. as by rods 37 and turnbuckle 40.FIGS. I and 2. the ring is deflected to reduce the chordal dimensionthereof sufficiently within its elastic limit. to permit the contractedring to be inserted in the circular series. of blades 17. mounted in thehalf of the stator housing 13.

Referring to FIG. I, the aperture in the contracted ring 30, adjacentone end thereof. is placed over the journal of the blade I7 at thecorresponding end of the series of blades. The ring is then rockeddownwardly whereby the journals of the blades successively enter theapertures ofthe ring. In FIG. 2. the ring has been rocked downwardly toa position where the journal of the blade at the center of the series isabout to enter the corresponding aperture in the ring. The turnbuckle 40is then released permitting the ring to expand to normal contour.whereby the journals of the remaining blades 17 in the series enter theremaining apertures in the ring. The expanded ring being indicated bydotted outline 41, FIG. 2.

Annular bearing members are then inserted in the space between theperiphery of each collar 25 and the bore of the aperture 33. Thebearings have a snug fit with the bore in the apertures. and a closerunning fit with the collars 25. The bores of the apertures are formedwith circular grooves to receive snap rings SI. FIG. 4. Thrust washers53 are positioned between the snap ring and the bearings 50. Wlth thisarrangement. the bearings are detachably interlocked with the ring 30,and a thrust structure is provided for the journaled stator blades 17.Because of the structure and mounting method described. the inner shroudrings 30 are economically produced by a turning operation. and arecompleted by the drilling and grooving of the apertures 33. The ringsmay be formed circular and subsequently split to provide the twointegral semi-circular sections for use in each stage of the machine.This one-piece formation of the shroud ring greatly reduces the time andeffort in the assembly of the shroud rings in the machine.

The stator housing 13, illustrated in FIGS. 1 and 2, may be the halfsection of the housing associated with the bottom half of the machinecasing. After the stator blades 17 have been assembled in the statorhousing for each stage. and the ring 30 attached to the inner ends ofthe blades. the rotor assembly is lowered into the machine.

The upper halfof the machine casing is then supplied with the statorblades. and the shroud rings 30 applied to those blades in like manner.That assembly is then inverted and placed upon the lower half of thecasing and affixed thereto. It will be apparent that our inven' tionprovides adequate support for the journaled stator blades. and alsomaterially reduces the time and expense in the assembly of the machine.

It will be noted that the shroud ring assembly struc ture of ourinvention permits the shroud ring to be formed in two semi-circularsections which are manufactured at low cost and are easily and quicklyassembled in the machine. in addition. the construction serving as thesubject matter of this invention provides a more reliable structure'thanin previous shroud ring constructions. as for example. the two-piecebolted sections adapted to clamp the inward projecting ends of thestator blades at opposite sides thereof as disclosed in U.S. Pat. No.3.269.701.

While we have described a preferred embodiment of our invention. it isto be understood that the invention is not limited thereto. but may beotherwise embodied within the scope of the following claims.

We claim:

1. The method of assembling an arcuate shroud ring to the inner ends ofan arcuate series of stator blades extending in a radial directioninwardly from a machine casing, the ring having apertures spaced apartcircumferentially for receiving in registration therewith said bladeends, the method including contracting the shroud ring by applying aforce thereto to reduce the diameter of the shroud ring to a diameterless than that described by the ends of the blades in the series wherebyat least one blade receiving aperture in the ring is insertable into oneof said blade ends,

inserting said one aperture into said one blade end.

and

relieving said contracting force to permit the shroud ring to expandwhereby the remaining apertures move into receiving registration withthe remaining blade ends in said series.

2. The method of claim 1 wherein said one blade end is carried on thelast blade in said series.

3. The method of claim 2 wherein the shroud ring is semi-circular inform.

1. The method of assembling an arcuate shroud ring to the inner ends ofan arcuate series of stator blades extending in a radial directioninwardly from a machine casing, the ring having apertures spaced apartcircumferentially for receiving in registration therewith said bladeends, the method including contracting the shroud ring by applying aforce thereto to reduce the diameter of the shroud ring to a diameterless than that described by the ends of the blades in the series wherebyat least one blade receiving aperture in the ring is insertable into oneof said blade ends, inserting said one aperture into said one blade end,and relieving said contracting force to permit the shroud ring to expandwhereby the remaining apertures move into receiving registration withthe remaining blade ends in said series.
 2. The method of claim 1wherein said one blade end is carried on the last blade in said series.3. The method of claim 2 wherein the shroud ring is semi-circular inform.